Magnetic anastomosis devices with varying magnetic force at a distance

ABSTRACT

Magnetic anastomosis devices constructed from magnetic segments coupled together with members that help the devices spontaneously transform from a linear delivery configuration to a polygonal deployment configuration. When two devices are joined together over tissue(s), the compressive force causes the tissue(s) to necrose and form an anastomosis. By altering the arrangement of the magnetic poles of the magnetic segments in the devices, the magnetic interaction between paired devices can be altered. This property gives surgeons flexibility in choosing how much attractive force the devices will experience during a procedure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and priority to, U.S.Provisional Application Ser. No. 62/132,075, filed Mar. 12, 2015, thecontent of which is hereby incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The invention relates to deployable magnetic compression devices andtheir use for creating anastomoses, e.g., in the gastrointestinal tract.The devices are especially useful for minimally-invasive delivery, e.g.,using endoscopic and/or laparoscopic techniques.

BACKGROUND

Bypasses of the gastroenterological (GI), cardiovascular, or urologicalsystems are typically formed by cutting holes in tissues at twolocations and joining the holes with sutures or staples. A bypass istypically placed to route fluids (e.g., blood, nutrients) betweenhealthier portions of the system, while bypassing diseases ormalfunctioning tissues. The procedure is typically invasive, andsubjects a patient to risks such as bleeding, infection, pain, andadverse reaction to anesthesia. Additionally, a bypass created withsutures or staples can be complicated by post-operative leaks andadhesions. Leaks may result in infection or sepsis, while adhesions canresult in complications such as bowel strangulation and obstruction.While traditional bypass procedures can be completed with an endoscope,laparoscope, or robot, it can be time consuming to join the holes cutinto the tissues. Furthermore, such procedures require specializedexpertise and equipment that is not available at many surgicalfacilities.

As an alternative to sutures or staples, surgeons can use mechanicalcouplings or magnets to create a compressive anastomosis betweentissues. For example, compressive couplings or paired magnets can bedelivered to tissues to be joined. Because of the strong compression,the tissue trapped between the couplings or magnets is cut off from itsblood supply. Under these conditions, the tissue becomes necrotic anddegenerates, and at the same time, new tissue grows around points ofcompression, e.g., on the edges of the coupling. With time, the couplingcan be removed, leaving a healed anastomosis between the tissues.

Nonetheless, the difficulty of placing the magnets or couplings limitsthe locations that compressive anastomosis can be used. In most cases,the magnets or couplings have to be delivered as two separateassemblies, requiring either an open surgical field or a bulky deliverydevice. For example, existing magnetic compression devices are limitedto structures small enough to be deployed with a delivery conduit e.g.,an endoscopic instrument channel or laparoscopic port. When thesesmaller structures are used, the formed anastomosis is small and suffersfrom short-term patency.

An additional difficulty arises in that a surgeon typically cannotcontrol the amount of magnetic attraction between deployable magneticstructures used to create an anastomosis. In some instances, it isbeneficial for the magnetic devices to couple strongly at distances over1 cm, however, in other instances, it is beneficial if the devicescouple weakly at over 1 cm, and then lock together at a smallerdistances. When the magnetic force is stronger than needed for aprocedure, the devices may “jump” or spontaneously move together beforethe surgeon is ready for the devices to couple and may inadvertentlytrap tissues that are not intended to be joined.

Thus, there still remains a clinical need for reliable devices andminimally-invasive procedures that facilitate compression anastomosisformation between tissues in the human body.

SUMMARY

The invention provides improved devices and techniques forminimally-invasive formation of anastomoses within the body, e.g., thegastrointestinal tract. Such devices and techniques facilitate fasterand less-expensive treatments for chronic diseases such as obesity anddiabetes. Such techniques also reduce the time and pain associated withpalliative treatments for diseases such as cancers, such as stomach orcolon cancer.

The invention provides multiple configurations of magnetic devicescomprising an assembly of magnetic segments that can be used to createanastomoses in a subject. Some of the devices are self-opening, anddesigned to be delivered via a trocar using laparoscopic techniques. Theself-opening devices are constructed from an assembly of magneticsegments including connection members between adjacent segments. Some ofthe connection members may serve as hinges so as to allow adjacentmagnetic segments to move relative to one another, particularly when thedevice transitions between delivery and deployed configurations, whileone or more of the connection members may serve as a spring or otherdevice for directing the magnetic segments to open to form a polygon.

For example, in one embodiment, the device includes an assemblyincluding a first pair of magnetic segments coupled together with afirst connection member and a second pair of magnetic segments coupledtogether with a second connection member. The assembly includes adelivery configuration in which the magnetic segments are aligned in tworows, the two rows being joined by the first and second connectionmembers or one or more additional connection members coupling the firstand second pairs of magnetic segments to one another. The assemblyfurther includes a deployed configuration in which the magnetic segmentsform an open polygon based, at least in part, on a force provided by atleast one of the first and second connection members or the additionalconnection members. Accordingly, at least one of the first and secondconnection members includes a spring, so as to direct the magneticsegments to open upon deployment.

The devices of the invention include a variety of configurationsconstructed from magnetic segments. Each magnetic segment has a northand a south magnetic pole. A device of the invention may include, forexample, four segments allowing the deployed device to take the shape ofa square. Alternatively, the device may include eight segments, allowingthe device to take the shape of an octagon. Other arrangements are alsofeasible, including hexagons, decagons, dodecagons, tetradecagons,hexadecagons, etc.

In the deployed configuration, the polygon has a top and a bottom, andthe magnetic segments can be arranged such that all or some of the northpoles of the magnetic segments are arranged toward the top of thepolygon. The inventors have discovered that for a given number ofmagnetic segments in a pair of devices, e.g., eight segments, differentarrangements of north and south poles will result in different magneticfields at a distance for the paired devices. However, the differentarrangements will experience approximately the same attractive magneticforce when the devices are in close proximity, i.e., touching. Thisfeature can be used to achieve variable magnetic force between paireddevices during a surgical procedure in which an anastomosis is to becreated. For example, if a surgeon decides after visualizing thesurgical field that he will need maximum force at a distance to bringthe tissues together, the surgeon may select a pair of devices in whichall of the north poles are arranged in the same direction. However, ifthe surgeon decides that he would like to have a greater flexibilitywhen arranging the devices, without having the devices coupleprematurely, the surgeon may select a pair of devices in which thearrangement of the north and south poles are alternating for eachmagnetic element.

Using the disclosed magnetic devices, it is possible to form anastomosesin patients in need of such treatment. In an embodiment, two deviceshave deployed configurations with identical sizes, shapes, and magneticpolar arrangement. However, each device will have a different deliveryconfiguration, thus allowing each device to be delivered with adifferent technique, e.g., one laparoscopically and one endoscopically.In an embodiment, one of the devices may include hinges at first andsecond ends of the device and polygon-opening members that direct themagnetic segments to open into a polygon upon deployment. This devicecan be delivered, e.g., via a trocar in a side-by-side deliveryconfiguration. The other device may be constructed from magneticsegments coupled together in a linear arrangement with polygon-closingmembers that direct the device to close and form a polygon upondeployment. This device can be delivered via the working channel of anendoscope in a linear configuration.

Because of the variation in magnetic force at a distance, and thedifferences in delivery configurations, it will be advantageous toprovide a set of matched devices in a kit. The kit may include aplurality of devices having the same delivery/deployment configurationbut having different magnetic polar arrangements, or the kit may includea plurality of devices with the same magnetic polar arrangement butdifferent delivery/deployment configurations. Other combinations ofdelivery/deployment configuration and magnetic polar arrangement arealso possible.

In one aspect, the invention provides a self-opening magneticcompression anastomosis device. The device includes an assembly of atleast four magnetic segments coupled end-to-end to form a polygon havingan out-of-plane axis, wherein each magnetic segment has a north magneticpole and a south magnetic pole. The assembly includes a first pair ofmagnetic segments coupled together with a first connection member and asecond pair of magnetic segments coupled together with a secondconnection member. The assembly includes a delivery configuration inwhich the magnetic segments are aligned in two rows, the two rows beingjoined by the first and second connection members or one or moreadditional connection members coupling the first and second pairs ofmagnetic segments to one another, and a deployed configuration in whichthe magnetic segments form an open polygon based, at least in part, on aforce provided by at least one of the first and second connectionmembers or the additional connection members.

In some embodiments, the first pair of magnetic segments have theirnorth poles aligned relative to one another with respect to theout-of-plane axis and the second pair of magnetic segments have theirnorth poles aligned relative to one another with respect to theout-of-plane axis. In some embodiments, the north poles of the firstpair of magnetic segments are aligned with the north poles of the secondpair of magnetic segments with respect to the out-of-plane axis. Inother embodiments, north poles of the first pair magnetic segments areanti-aligned with the north poles of the second pair of magneticsegments with respect to the out-of-plane axis.

In some embodiments, the first pair of magnetic segments have theirnorth poles anti-aligned relative to one another with respect to theout-of-plane axis and the second pair of magnetic segments have theirnorth poles anti-aligned relative to one another with respect to theout-of-plane axis. Yet still, in some embodiments, the north magneticpoles of the magnetic segments alternate in orientation with respect toa top and a bottom of the polygon from segment to segment.

In some embodiments, the assembly includes four magnetic segments. Thepolygon has a top and a bottom, and two magnetic segments have theirnorth magnetic poles arranged toward the top of the polygon and twoother magnetic segments have their north magnetic poles arranged towardthe bottom of the polygon. The north magnetic poles of the magneticsegments alternate in orientation with respect to the top and bottom ofthe polygon from segment to segment. The assembly includes a firstmagnetic segment, a second magnetic segment immediately adjacent to thefirst magnetic segment, a third magnetic segment immediately adjacent tothe second magnetic segment, and a fourth magnetic segment immediatelyadjacent to the third and first magnetic segments. The north magneticpoles of the first and third magnetic segments are arranged toward thetop of the polygon and the north magnetic poles of the second and fourthmagnetic segments are arranged toward the bottom of the polygon.

In some embodiments, the assembly includes eight magnetic segments suchthat the assembly further includes a third pair of magnetic segmentscoupled together with a third connection member and a fourth pair ofmagnetic segments coupled together with a fourth connection member. Whenin the delivery configuration, the magnetic segments are aligned in tworows, the two rows being joined by the first and third connectionmembers or one or more additional connection members coupling at leasttwo of the first, second, third, and fourth pairs of magnetic segmentsto one another, and a deployed configuration in which the magneticsegments form an open polygon based, at least in part, on a forceprovided by at least one of the first, second, third, and fourthconnection members or additional connection members.

When including at eight magnetic segments, the polygon has a top and abottom, and four magnetic segments have their north magnetic polesarranged toward the top of the polygon and four other magnetic segmentshave their north magnetic poles arranged toward the bottom of thepolygon. The north magnetic poles of the magnetic segments alternate inorientation with respect to the top and bottom of the polygon fromsegment to segment. The assembly includes a first magnetic segment, asecond magnetic segment immediately adjacent to the first magneticsegment, a third magnetic segment immediately adjacent to the secondmagnetic segment, a fourth magnetic segment immediately adjacent to thethird magnetic segment, a fifth magnetic segment immediately adjacent tothe fourth magnetic segment, a sixth magnetic segment immediatelyadjacent to the fifth magnetic segment, a seventh magnetic segmentimmediately adjacent to the sixth magnetic segment, and an eighthmagnetic segment immediately adjacent to the first and seventh magneticsegments. In embodiments, the north magnetic poles of the first, third,fifth, and seventh magnetic segments are arranged toward the top of thepolygon and the north magnetic poles of the second, fourth, sixth, andeighth magnetic segments are arranged toward the bottom of the polygon.

Yet still, in embodiments in which the assembly includes eight magneticsegments, four adjacent magnetic segments have their north magneticpoles arranged toward the top of the polygon and four other adjacentmagnetic segments have their north magnetic poles arranged toward thebottom of the polygon. The eight magnetic segments have their northmagnetic poles aligned in the same direction with respect to theout-of-plane axis.

In some embodiments, one or more of the connection members includes astainless steel, plastic, or nitinol material. In some embodiments, oneor more of the connection members includes a spring. In someembodiments, one or more of the connection members includes a hinge. Insome embodiments, one or more of the connection members is coupled tothe exterior of the polygon. The one or more of the connection membersmay be an exoskeleton.

The polygon may include at least one of a square, hexagon, octagon,decagon, dodecagon, tetradecagon, hexadecagon, octodecagon, andicosagon.

When in the delivery configuration, the assembly of magnetic segments issized to fit within a working channel of an access device and to bedelivered to an anatomical structure within a patient. The assembly isconfigured to spontaneously convert from the delivery configuration tothe deployed configuration once expelled from the working channel of theaccess device. The access device may include one of an endoscope, alaparoscope, a trocar, and a cannula.

In some embodiments, the assembly of magnetic segments is configured tobe coupled to a guide element and configured to translate along a lengthof the guide element when transitioning from the delivery configurationto the deployed configuration. In some embodiments, the guide elementmay include a guidewire configured to fit within the working channel ofthe access device and coupled to the self-opening magnetic compressionanastomosis device, wherein the assembly of magnetic segments isconfigured to translate along a length of the guidewire whentransitioning from the delivery configuration to the deployedconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the claimed subject matter will be apparentfrom the following detailed description of embodiments consistenttherewith, which description should be considered with reference to theaccompanying drawings, wherein:

FIG. 1 depicts two magnetic devices attracting each other throughtissue. The devices shown in FIG. 1 each comprise eight magneticsegments, however alternate configurations are possible. Once the twodevices mate, the tissue that is trapped between the devices willnecrose, causing an anastomosis to form. Alternatively, the tissue boundby the devices may be perforated after the devices mate to create animmediate anastomosis;

FIG. 2 depicts the creation of an anastomosis between organs of thegastrointestinal tract;

FIG. 3 depicts an octagonal device of the invention. The arrow depictsthe out-of-plane axis for the device and defines a top and bottom. Asshown in FIG. 3, the magnetic poles (N or S) of each magnetic segmentcan be arranged as desired. (For convenience, cross-hatching or shadingcorresponds to north magnetic pole);

FIGS. 4A-4E depict exemplary configurations of devices comprising eightmagnetic segments;

FIGS. 5A-5F depict exemplary configurations of devices comprising twelvemagnetic segments;

FIG. 6 shows a graphical depiction of the relationship betweenconfiguration of magnetic poles and attractive force at a distance fortwo paired devices having the same magnetic polar configuration;

FIG. 7 shows a graphical depiction of the relationship betweenconfiguration of magnetic poles and attractive force at a distance fortwo paired devices having the same magnetic polar configuration;

FIG. 8 depicts a kit containing a plurality of paired devices havingdiffering magnetic polar arrangements. The paired devices may have thesame or different delivery configurations;

FIG. 9A is a close-up view of a self-opening magnetic anastomosis deviceof the invention including connection members, such as hinges, at theends and polygon-opening members between adjacent magnetic segments. Inthe embodiment of FIG. 9A, all of the poles of the magnetic segments arearranged in the same direction;

FIG. 9B is a close-up view of a self-opening magnetic anastomosis deviceof the invention including connection members at the ends andpolygon-opening members between adjacent magnetic segments. In theembodiment of FIG. 9B, two of the bipolar magnets of FIG. 8 have beenreplaced with quadrupolar segments, which facilitate closure of theconnection members;

FIG. 9C is a close-up view of a self-opening magnetic anastomosis deviceof the invention including connection members at the ends andpolygon-opening members between adjacent magnetic segments. In theembodiment of FIG. 9C, half of the poles of the magnetic segments arearranged toward the top of the polygon and half of the poles of themagnetic segments are arranged toward the bottom of the polygon;

FIG. 9D is a close-up view of a self-opening magnetic anastomosis deviceof the invention including connection members at the ends andpolygon-opening members between adjacent magnetic segments. In theembodiment of FIG. 9D, the north poles of the magnetic elements coupledto the connection members are arranged toward the top of the polygon,and the middle elements have their poles directed to the bottom of thepolygon;

FIG. 10A is a close-up view of a self-opening magnetic anastomosisdevice of the invention including connection members at the ends andpolygon-opening members between adjacent magnetic segments. In theembodiment of FIG. 10A, the poles of the magnetic segments alternate indirection around the polygon;

FIG. 10B is a close-up view of a self-opening magnetic anastomosisdevice of the invention including connection members at the ends and twopolygon-opening members that span multiple adjacent magnetic segments.The polarities of the magnetic segments of FIG. 10B can be in anyconfiguration, e.g., as shown in FIGS. 9A-10A;

FIG. 11 depicts delivery of a self-opening magnetic anastomosis deviceof, e.g., FIGS. 9A-10A, through a trocar with the assistance of apusher. In some embodiments, specialty trocars, such as a trocar havinga rectangular cross-section or a round trocar having inserts, may beused to facilitate deployment of a self-opening device;

FIG. 12 depicts assembly of a self-closing magnetic anastomosis devicethat comprises a polygon-closing assembly (nitinol exoskeleton) andmagnetic segments. Once assembled, two of the self-closing devices canbe coupled together to form an anastomosis. The device of FIG. 12 hasthe magnetic poles of all eight magnets arranged in the same direction;

FIG. 13 depicts assembly of a self-closing magnetic anastomosis devicethat comprises a polygon-closing assembly (nitinol exoskeleton) andmagnetic segments. The device of FIG. 13 has half of the poles of themagnetic segments arranged toward the top of the polygon and half of thepoles of the magnetic segments arranged toward the bottom of thepolygon;

FIG. 14 depicts assembly of a self-closing magnetic anastomosis devicethat comprises a polygon-closing assembly (nitinol exoskeleton) andmagnetic segments. The device of FIG. 14 has half of the poles of themagnetic segments arranged toward the top of the polygon and half of thepoles of the magnetic segments arranged toward the bottom of thepolygon;

FIG. 15 depicts assembly of a self-closing magnetic anastomosis devicethat comprises a polygon-closing assembly (nitinol exoskeleton) andmagnetic segments. In the embodiment of FIG. 15, the poles of themagnetic segments alternate in direction around the polygon;

FIG. 16 depicts delivery of a self-closing magnetic anastomosis deviceof, e.g., FIGS. 12-15, through the working channel of an endoscope withthe assistance of a pusher;

FIG. 17 shows an embodiment of a guide element coupled to a magneticsegment of a device of the invention. Alternate methods of coupling theguide element to the magnetic segment are also described herein;

FIGS. 18A-18D depict an embodiment of a self-opening magneticanastomosis device that includes a guide element coupled to an magneticsegment, wherein the guide element facilitates placement of the magneticdevice in a deployment configuration;

FIGS. 19A-19D depicts an embodiment of a self-opening magneticanastomosis device that includes a guide element coupled to a pluralityof radial elements coupled to magnetic segments, wherein the guideelements facilitates placement of the magnetic device in a deploymentconfiguration;

FIGS. 20A-20D depict an embodiment of a self-opening magneticanastomosis device that includes two guide elements coupled to theconnection members, wherein the guide element facilitates closure of thedevice and placement of the magnetic device once in a deploymentconfiguration;

FIGS. 21A-21D depict deployment of a self-opening magnetic device usinga guidewire. The self-opening device is advanced over the guidewire witha pusher while the device is kept in a delivery configuration by asheath. Once the device is in place, the sheath can retracted allowingthe device to assume a deployment configuration. The embodiment shown inFIGS. 21A-21D may additionally include one or more guide element(s) (notshown) to facilitate closure of the device and placement aftertransforming into a deployment configuration;

FIG. 22 depicts an embodiment of a self-closing magnetic anastomosisdevice that includes a guide element coupled to an magnetic segment. Theguide element facilitates placement of the magnetic device in adeployment configuration;

FIG. 23 depicts an embodiment of a self-closing magnetic anastomosisdevice that a guide element coupled to a plurality of radial elementscoupled to magnetic segments. The guide elements facilitates placementof the magnetic device in a deployment configuration;

FIG. 24 depicts calculations of potential wells in an octagonalself-opening device having an NNNN alignment;

FIG. 25 depicts calculations of potential wells in an octagonalself-opening device having an NNNS alignment;

FIG. 26 depicts calculations of potential wells in an octagonalself-opening device having an NNSN alignment;

FIG. 27 depicts calculations of potential wells in an octagonalself-opening device having an NNSS alignment;

FIG. 28 depicts calculations of potential wells in an octagonalself-opening device having an NSSN alignment; and

FIG. 29 depicts calculations of potential wells in an octagonalself-opening device having an NSNS alignment.

For a thorough understanding of the present disclosure, reference shouldbe made to the following detailed description, including the appendedclaims, in connection with the above-described drawings. Although thepresent disclosure is described in connection with exemplaryembodiments, the disclosure is not intended to be limited to thespecific forms set forth herein. It is understood that various omissionsand substitutions of equivalents are contemplated as circumstances maysuggest or render expedient.

DETAILED DESCRIPTION

The invention includes self-opening and self-closing polygonal magneticdevices that couple to each other with substantial compressive magneticforce. The invention makes it possible to create surgical anastomoses intissue quickly with minimally-invasive techniques such as endoscopy andlaparoscopy. Once the devices have are placed and mated, the compressiveforces cause the vasculature of the tissue to collapse and fluids toextrude from the tissues, reducing the distance between the devices andincreasing the magnetic attraction. With time, the coupled deviceseventually mate completely, form an opening, and fall away from thetissue, leaving an anastomosis. The magnetic devices can, thus, be usedto create surgical-quality anastomosis without the need to create anopen surgical field.

With the described technique it is simpler to create openings betweentissues that traditionally required open surgery or the use ofcomplicated cutting and suturing devices. Most procedures are reduced tosimply delivering a first magnetic compression device to a first tissueand then delivering a second magnetic compression device to a secondtissue, and then bringing the two devices together. For example, it isstraightforward to create a gastric bypass by delivering first andsecond magnetic devices, in the form of octagons, to the stomach and thesmall intestine. The magnetic force of the two devices eventuallycreates an anastomosis that leads from the stomach to the smallintestine, reducing the working volume of the stomach.

The devices of the invention generally comprise magnetic segments thatcan assume a delivery conformation and a deployed configuration. Thedelivery configuration is typically linear so that the device can bedelivered to a tissue via a laparoscopic “keyhole” incision or withdelivery via a natural pathway, e.g., via the esophagus, with anendoscope or similar device. Additionally, the delivery conformation istypically somewhat flexible so that the device can be guided throughvarious curves in the body. Once the device is delivered, the devicewill assume a deployed configuration of the desired shape and size byconverting from the delivery configuration to the deployed configurationautomatically. The self-conversion from the delivery configuration tothe deployment configuration is directed by coupling structures thatcause the magnetic segments to move in the desired way withoutintervention.

As shown in FIG. 1 two devices 10 and 20 are brought to opposite sidesof tissues 30 and 40, in which an anastomosis is to be formed. Once thetwo devices 10 and 20 are brought into proximity, the devices 10 and 20mate and bring the tissues 30 and 40 together. With time, an anastomosisof the size and shape of the devices 10 and 20 will form and the deviceswill fall away from the tissue. Alternatively, because the mated devices10 and 20 create enough compressive force to stop the blood flow to thetissues 30 and 40 trapped between the devices, a surgeon may create ananastomosis, by making an incision in the tissues 30 and 40circumscribed by the devices. In yet another embodiment, a surgeon mayfirst cut into the tissue, e.g., tissue 30, and then deliver the device10 around the incision and then couple the second device 20 to the firstdevice so that the devices 10 and 20 circumscribes the incision. Asbefore, once the devices mate, the blood flow to the incision is quicklycut off. The mating device 20 may be delivered in the same way, e.g.,through an incision, or the mating device 20 can be delivered via adifferent surgical route, e.g., via an endoscope.

During the procedure, the position of the two devices 10 and 20 can bevisualized directly, e.g., using an endoscopic or laparoscopic camera.In other instances, the two devices 10 and 20 can be monitored withultrasound or another medical imaging technique, such as fluoroscopy. Insome embodiments, the visualization will be provided with the deliverydevice. In some embodiments, the visualization will be achieved with aseparate device. Other techniques, known in the art, such as dyes,contrast, and gas delivery may also be used to assist visualization ofthe mating devices.

As described in greater detail below, the design of the devices 10 and20 can be customized depending upon the surgical techniques that will beused and the specific needs of the patient. The design specificationsmay include: required capture range, desired effective inner and outerdiameters of the magnetic device (e.g., as defined by the desiredanastomosis size and instrument passage), thickness of the targettissue, and the inner diameter of the guiding channel and the smallestradius of curvature to which the guiding channel may be bent and throughwhich the magnets must pass. Once the design specifications are chosen,corresponding magnetic device designs can be determined, such aspolygon-side-count and length, and the maximum lateral dimensions of theflexible linear magnetic structure that will be deployed through thedelivery instrument. Additionally, as described below, the arrangementsof the magnetic segments that make up the device may be altered tocustomize the amount of force between the devices 10 and 20 at adistance, e.g., at 1 cm or further apart.

Using the techniques outlined above, it is possible to createanastomoses between a variety of tissues and organs in thegastrointestinal tract, as depicted in FIG. 2. For example, anastomosesmay be formed between the stomach, small intestine, gall bladder, andcolon, as shown in FIG. 2. Such techniques can be used for management ofdisease, such as obesity and diabetes, or such techniques can be used toimprove function in the wake of disease, such as cancer. Such techniquescan also be used for repair, for example, to connect portions of healthycolon after a portion of diseased colon has been removed. Suchprocedures can be accomplished endoscopically, laparoscopically, with anopen surgical field, or with some combination of these techniques.

A device of the invention, generally, includes a plurality of magneticsegments that assume the shape of a polygon once deployed in a patient.The magnetic segments are typically formed from rare earth magnets. Themagnetic segments may be mitered. The magnetic segments may be coatedwith gold or plastic to improve their performance. A general depictionof an octagonal device is shown in FIG. 3, however it is to beunderstood that a variety of deployed shapes are feasible using the sameconstruction, such as squares, hexagons, decagons, dodecagons,tetradecagons, hexadecagons, octodecagons, and icosagons. As shown inFIG. 3, each magnetic segment of the device has at least at least twopoles, north “N” and south “S,” with the poles oriented normal to theface of the polygon. For convention, the north magnetic poles of thesegments of the application are sometimes cross-hatched, while the southmagnetic poles are solid (or not cross-hatched). As shown in FIG. 3, anout of plane axis can be defined that runs through the center of thepolygon and normal to the face of the polygon, defining a “TOP” and a“BOTTOM” of the device. (It is understood that “TOP” and “BOTTOM” arearbitrary, but correspond to different sides of the polygon.)

Because each magnetic segment has at least one north pole and at leastone south pole, it is possible to create devices of the invention with avariety of magnetic polar configurations. For example, the device shownin FIG. 3 includes four magnetic segments arranged toward the top of thepolygon, and four magnetic segments arranged toward the bottom of thepolygon. Furthermore, as show in FIG. 3, the four magnetic segmentsarranged toward the top of the polygon are all adjacent each other. Sucha configuration may be written N/N/N/N/S/S/S/S or NNNNSSSS, or N4/S4.Other arrangements of the magnetic poles are possible in an octagonaldevice, such as shown in FIG. 4. For example, all of the poles can bearranged in the same direction, i.e., N/N/N/N/N/N/N/N or N8 (top left ofFIG. 4), or the magnetic poles can be alternated in each segment, i.e.,N/S/N/S/N/S/N/S or NSNSNSNS (bottom of FIG. 4). Other configurations ofthe magnetic poles are also available, such as N/S/N/SS/N/S/N orN2SNS2NS, or N/SS/NN/SS/N or N2S2N2S2, or NN/SSSS/NN or N2S4N2, allshown in FIG. 4.

The variety in magnetic polar configuration can be extended to othergeometries with fewer or greater numbers of magnetic segments. Forexample, as shown in FIG. 5, a device with 12 segments can be arrangedwith N12, N6S6, N3S3N3S3, N2SNSNS2NSNS, N2SN2S4N2S, or NSNSNSNSNSNS. Ofcourse, the mirror images are also possible, such as S2NS2N4S2N, howeversuch configurations are actually identical when viewed from the otherside. The same principles can be used for devices that have fewersegments, for example, four segments (N4, N2S2, and NSNS), or sixsegments (N6, N3S3, N2S2NS, and NSNSNS). The same principles can be usedfor devices that include more than twelve segments, for example, sixteensegments (N16, N8S8, N6SNS6NS, N4S4N4S4, N4S2N2S4N2S2, N4SNSNS4NSNS,N3SN3SNS3NS3, N2S2N2S2N2S2N2S2, N2S2NSNSN2S2N2S2, N2S2NSN2S2NSN2S2, andNSNSNSNSNSNSNSNS).

The benefits of differing magnetic polar configurations are illustratedin FIG. 6. As depicted in the graph of FIG. 6, the relative attractiveforce between two octagons of identical magnetic polar configuration, asthe devices are brought closer together, is a function of magnetic polarconfiguration. However, the total attractive force when devices of thesame number of segments are brought into contact should be roughly thesame. (The units on both axes are arbitrary, as is the variation betweenthe curves.) In general, two devices having the magnetic poles of all ofthe magnetic segments arranged in the same direction with respect to topof the polygon experience the greatest amount of magnetic attraction ata distance (N8; solid line), while two devices having alternatingmagnetic poles in the magnetic segments have the least amount ofmagnetic attraction at a distance (NSNSNSNS; dot-dashed line).Intermediate to these two extremes are configurations in which thesimilarly-aligned magnetic segments are next to each other but not allpoles are arranged in the same direction, i.e., N4S4 (long dashed line)and staggered configurations such as N2SNS2NS (short dashed line). Otherconfigurations, not shown in the graph of FIG. 6, such as N7S, N5SNS,etc., would also have curves somewhere between the N8 curve and theNSNSNSNS curve. FIG. 7 shows actual force measurements made by securingmagnetic arrangements in epoxy and bringing them toward each other witha dynamometer. As can be seen in FIG. 7, there is marginal difference inforce at a distance between N8 and N4S4 octagons. It should be notedthat, as shown in FIG. 7, there is a wide variation of force at adistance of approximately 1 cm (10 mm).

Accordingly, by selecting a particular configuration, a surgeon can“tune” the interaction between devices for the desired performance.Thus, if it is necessary to maximize force at a distance to facilitatebringing tissues together, a surgeon can use two devices with all of thepoles arranged in the same direction, i.e., N8. If, on the other hand,the placement of the devices was critical, and the surgeon wanted tominimize the chance that the devices mated before necessary, the surgeoncould use a configuration with alternating magnetic poles, i.e.,NSNSNSNS. In fact, for some procedures, it may be useful to provide akit of matched devices with varying magnetic polar configurations, suchas shown in FIG. 8. Such a kit would allow a surgeon to choose a desiredconfiguration during the procedure, based upon visualization of thesurgical field after the procedure has started. Alternatively, such akit could provide “back-up,” in the form of stronger-attracting devices,if the surgeon encountered difficulties joining the tissues during theprocedure.

While not wishing to be limited by theory, it is believed that thevariability between different magnetic polar configurations is afunction of how much interaction a given magnetic pole has with segmentsof the same polarity on the mating device. That is, at intermediatedistances, i.e., between no interaction and touching, each magnetic poleis interacting with multiple magnetic segments on the mating device. Inthe instance where mating devices comprise segments with alternatingpoles, a magnetic segment from a first device interacts with at leastone opposite pole and two same poles on a nearby mating device. The samepole repulsions cancel out a good portion of the opposite poleattraction, resulting in less aggregate attraction at distances of about1 cm or more. In the other extreme, a segment of a device having all ofthe poles arranged in the same direction would only experienceattractive forces between it and the segments of the mating device.

Nonetheless, regardless of magnetic polar arrangements, once the twodevices are brought together, most of the interaction is between asegment of the first device and the corresponding segment on the matingdevice. Accordingly, the total attractive force between devices ofdifferent configurations is about the same once the devices are joined.

In a similar fashion, devices of differing numbers of segments, i.e.,squares, hexagons, octagons, decagons, dodecagons, tetradecagons,hexadecagons, octodecagons, and icosagons can be tuned by selectingparticular arrangements of magnetic poles. There are also additionalreasons that a particular configuration of magnetic poles may be chosen,for example, to cause the devices to overlap correctly, or to cause thedevices to connect in a way that insures that the devices cannot revertto their delivery configuration. See e.g., US 2013/0253550, incorporatedherein by reference in its entirety.

The variability in magnetic polar orientation, described above, can beused in a variety of deployable magnetic devices, including bothself-opening and self-closing devices, as described below. For example,self-opening devices may be constructed having a variety of magneticpolar arrangements, as shown in FIGS. 9A-10B. Additionally, self-closingdevices may be constructed having a variety of magnetic polararrangements, as shown in FIGS. 12-15. As shown in FIGS. 11 and 16, thetwo configurations (self-opening and self-closing) lend themselves todeployment with different methods, i.e., laparoscopy and endoscopy,respectively. Accordingly, various combinations of devices can beselected, as required, based upon the surgical approach, and therequirements of the anatomy of the patient.

In some embodiments of the invention, the deployable magnetic device isself-opening, i.e., as shown in FIGS. 9A-10B. Each device comprises anumber of magnetic segments 810, wherein two pairs of magnetic segmentsare linked together at each end with a connection member 830, such as ahinge. The magnetic segments 810 between the connection members 830 arelinked together with additional connection members 850, which areconfigured to direct the device to self-convert from a delivery 870 to adeployed 890 configuration. It should be noted that the term “connectionmember” may be used herein to refer to a hinge or a polygon-openingmember, depending on the application. For example, connection member 830may be referred to herein as a “hinge”, which connection member 850 maybe referred to herein as a “polygon-opening member”.

While the polygon-opening members 850 are shown coupled to the exteriorof the magnetic segments in FIGS. 9A-10B, the polygon-opening membersmay also be coupled to the interior of the magnetic segments. In someinstances, the polygon-opening members form an exoskeleton over themagnetic segments. The polygon-opening members may be bonded or fastenedto the magnetic segments or the polygon-opening members can crimp orgrab the magnetic segments.

While each self-opening device comprises two hinges, the number ofpolygon-opening members 850 depends upon the total number of magneticsegments in the device. For example, for a device that takes theconfiguration of a square upon deployment, the device will comprise fourmagnetic segments 810, two hinges 830, and two polygon-opening members850. As shown in FIGS. 9A-10B, an octagonal self-opening device mayinclude eight magnetic segments 810, two hinges 830, and sixpolygon-opening members 850. In alternate embodiments, a singularpolygon opening member may span two or more magnetic segments 810 (shownin FIG. 10B). In alternative embodiments, as shown in FIG. 9B, aquadrupolar magnetic segment can be used at the hinge end to improveopening. Quadrupolar segments are not limited to octagonalconfigurations, and can be used with any of the configurations describedherein. Thus, it is possible to construct a self-opening octagonaldevice with eight magnetic segments 810, two hinges 830, and twopolygon-opening members (see FIG. 10B). Using the same techniques it ispossible to construct deployable self-opening devices having differentnumbers of magnetic segments that deploy as, e.g., squares, hexagons,decagons, dodecagons, tetradecagons, hexadecagons, octodecagons, oricosagons.

The self-opening devices of the invention can incorporate a variety ofmagnetic polar configurations, as shown in FIGS. 9A-10B. However,because of the devices need to self-convert between a side-by-sidearrangement and an open polygon, it is beneficial to place the hingessuch that similarly-aligned magnetic poles are next to each other in thedelivery configuration. For example, as shown in FIG. 10A, each segmentin the delivery configuration is next to a segment of the same magneticorientation so that, upon delivery, the magnetic repulsions betweensegments drives the device into the open (deployed) configuration. Insuch a configuration, the primary role of the polygon-opening member isto insure that the device opens in the plane of the polygon; i.e., thatout-of-plane motion of the magnetic segments is limited. The hinges ofthe self-opening devices may be constructed from metal (stainless steel,nickel, or nitinol) or plastic, and the hinges may be passive or active,i.e., configured to provide an opening force. In some instances, thehinges are springs. The polygon-opening members may be constructed fromconstructed from metal (stainless steel, nickel, or nitinol) or plastic.The polygon opening members are typically active in that they provide aforce to drive the device from a delivery configuration to a deploymentconfiguration.

An alternate construction of an eight segment, self-opening device ofthe invention is shown in FIG. 10B. In the embodiment of FIG. 10B, onlytwo polygon-opening members 850 are needed to direct the device to openproperly. Like other self-opening devices, the device includes twohinges 830 that help the device transform from a delivery configuration(bottom left) to a deployed configuration (bottom right). The deviceshown in FIG. 10B may be constructed by first coupling two pairs ofmagnetic segments 810 with hinges 830, and then arranging the remainingmagnetic segments 810 in a deployed configuration. Each polygon openingmember 850 can then be coupled to four segments, including one segmentof each hinged pair, to complete the assembly (top of FIG. 10B). Thepolygon opening members 850 may be bound, coupled, or attached to themagnetic segments. Alternatively, as shown in FIG. 10B, the polygonopening members 850 may envelop the magnetic segments, e.g., as anexoskeleton. While it is not shown in FIG. 10B, it is understood thatthe polarities of the magnetic segments 810 can be configured as desiredto achieve specific performance at a distance, i.e., as discussed abovewith respect to FIGS. 3-6. Additionally, the construction shown in FIG.10B is not limited to eight magnetic segments, as a polygon-openingmember 850 can be coupled to many magnetic segments, such as two, three,four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen,fourteen, or fifteen magnetic segments.

The self-opening devices of the invention are designed to be deliveredin a side-by-side configuration as shown in FIG. 11. In thisconfiguration, a self-opening device can be inserted through a trocar1100 or other cannula to a location within a patient where the devicewill be deployed and coupled to a mating device. Typically, a pusher1130 will be used to extract the self-opening device from the trocar1100. Once the device is pushed from the trocar 1100, the device willspontaneously open to form a polygon, as shown in FIGS. 9A-10A. Thetrocar 1100 may be round in cross-section, or the trocar 1100 may berectangular in cross-section to help the self-opening device to remainin a flat delivery configuration while it is delivered. (See right sideof FIG. 11.) In other embodiments, non-magnetic inserts 1150, orextruded shaped tubing, may be used to facilitate delivery of aself-opening device. Other configurations of self-opening devices, i.e.,squares, hexagons, decagons, dodecagons, tetradecagons, hexadecagons,octodecagons, and icosagons, can also be delivered in a similar manner.In some instances, the pusher may have a lumen for a guide element asdiscussed below. In some instances, a laparoscopic manipulator (notshown) will be used to facilitate placement of the deployed device.

Because of the construction, the magnetic devices of the invention arerelatively smooth and flat and present essentially uninterrupted annularfaces. Because of this design, the devices do not cut or perforatetissue(s), but rather achieve anastomosis by providing steadynecrotizing pressure across the contact surface between mating deployeddevices. These features also reduce the risks associated with surgicalaccess and ensure that the anastomosis is formed with the correctgeometric attributes. Overall, the design ensures the patency of theanastomosis.

Like the self-opening devices of FIGS. 9A-10B, the self-closing devicesof the invention can incorporate a variety of magnetic polarconfigurations, as shown in FIGS. 12-15. As shown in FIG. 12, aself-closing magnetic compression device 100 can be formed by deliveringa polygon-closing assembly 120 to a set of magnetic segments 140. Thepolygon-closing assembly 120 may be made from a resilient material thatwill retain its shape after deformation, such as a polymer or metalalloy. In some embodiments, the metal alloy will comprise nickel, suchas nitinol. The magnetic segments 140 may be comprised of anystrongly-magnetic material, such as rare earth magnetics, comprisingmaterials such as neodymium, samarium, erbium, yttrium, ytterbium, andcobalt. In some embodiments, the magnetic segments may be coated, e.g.,with gold or Teflon, to improve durability or biocompatibility. Onceassembled, the resulting self-assembling magnetic anastomosis device canbe intentionally deformed into a semi-linear shape, but will form apolygon when released, as shown in FIG. 12.

During deployment, the polygon-closing assembly 120 acts as a hingebetween magnetic segments 140 while coupling the structural rigidity ofindividual segments 140 similar to a cantilevered beam. In other words,the tensile modulus of the polygon-closing assembly 120 and thepolygon-closing assembly's resistance to out-of-plane bending allow theforces on the distal end of the structure to be distributed across themagnetic segments 140. The design allows a pushing force on the proximalend of the device in a delivery configuration to reliably move thedistal end of the device, e.g., out of a deployment lumen such as theworking channel of an endoscope. Because the polygon-closing assembly120 is thin, and in close contact with the magnetic segments that arelong relative to the length of their miter joints, the polygon-closingassembly 120 can bend to accommodate miter closure with relatively smallstrain. However, the breadth of the polygon-closing assembly 120produces a high moment of inertia (stiffness) againstout-of-polygonal-plane bending, thereby giving good guidance of thegrowing ring and providing lateral resistance to deflection duringclosure. Finally, the polygon-closing assembly 120 also provides atensile coupling between the magnetic segments, assuring that thesegments do not go past the closure point and collapse inward or overtop of one-another.

As show in FIG. 12, two self-assembling magnetic compression devices 100can be associated as a matched set 180. As described above, tissues thatare trapped between the matched set 180 will be compressed, andeventually grow together, leaving an opening 160 in the tissue. As shownin FIG. 12, each magnetic segment of the matched set 180, has at leastat least two poles 183 and 185, with the poles oriented normal to theface of the polygon. When assembled, the poles of the segments inadjoining devices are arranged N/S/N/S or S/N/S/N. The aligned andmatching poles in the matched set 180 form a very strong couplingbetween the two elements. Additionally, the attractive forces betweenopposing poles of nearby magnetic segments facilitates assembly ofmatched set 180. Typically, the two elements of the matched set 180 needonly to be placed in proximity to each other and the magnetic segmentswill self-align in the preferred configuration. In some instances, it isnecessary to pre-align the complimentary devices, however, in otherinstances the devices self-align by undergoing fast in-plane rotationwith respect to one another.

Additionally, like the self-opening devices of FIGS. 9A-10B, theself-closing devices of FIGS. 12-15 can have a variety of magnetic polararrangements, giving a user the ability to tune the amount of attractiveforce between devices at a distance. Typically, the arrangement of themagnetic segments is preset prior to attachment of the polygon-closingassembly 120, as shown in FIGS. 12-15. Because the polygon-closingassembly is non-magnetic, the completed self-closing device will havesegments with polarities dictated by the polarities of the underlyingmagnetic segments 140, as shown in FIGS. 13-15. Again, the octagonalstructures of FIGS. 12-15 are illustrative, and should not be seen aslimiting. In other words, self-closing structures that create squares,hexagons, decagons, dodecagons, tetradecagons, hexadecagons,octodecagons, or icosagons can be formed in a similar manner.Additionally, self-closing magnets may be constructed from an odd numberof magnetic segments, including magnetic bipoles, as shown in thedrawings, or magnetic quadrupoles, hexapoles, or octapoles, as may berequired. It is not necessary that each magnetic segment is the samesize or length.

Accordingly, the self-closing devices, constructed from linked magneticmultipole segments 140, will form a polygon when extruded from the endof a delivery lumen, e.g., through a trocar or a working channel of anendoscope 200, as shown in FIG. 16. As each successive magnetic segment140 emerges from the end of the working channel 200 into the surgicalfield, the polygon-closing assembly 120 constrains the segment againstout-of-polygonal plane deflection and the segments' mutual attractionsclose each miter joint 260 in the correct inward direction, sequentiallycorrect and, as the last segment is extruded, to close the polygonalmagnetic ring. Furthermore, when the devices are constructed withsymmetric miter joints and have their magnetic poles aligned with theannular axis of the polygon, the total magnetic force normal to themating surfaces is maximized. The magnetic forces increase themechanical stability of a set of coupled magnets while speedinganastomosis formation due to the intense compressive force on thetrapped tissues.

In many instances, it is beneficial to be able to manipulate thelocation of a device after it has been delivered to a tissue. While thedevice can be manipulated with conventional tools such as forceps, it isoften simpler to manipulate the location of the deployed device with aguide element 220, such as a suture or wire. As shown in FIGS. 17,18A-18D, 19A-19D, 20A-20D, 21A-21D, and 22, a variety of attachmentpoints can be used to provide control over the location and deploymentof a self-opening or a self-closing magnetic anastomosis device. Theguide element 220 may extend proximally away from the surgical field andemerge, e.g., from a port or from the proximal end of the workingchannel of an endoscope.

For example, as shown in FIGS. 18A-18D and 22, the guide element 220 maybe coupled to a single distal segment such that, upon deployment, thesingle distal segment results in an attachment point that providestranslational freedom of movement. It is also notable that in theself-closing configuration shown in FIG. 22, the guide element 220allows a closing force to be applied to the distal-most segment. Thatis, in the event that one or more segments should become entangled withtissue, or otherwise prevented from closing, a proximal pulling forcewith the guide element 220 can help the device to completeself-assembly. Furthermore, once the device has achieved its deployedconfiguration, the device can be positioned with the guide element 220to be mated with another device (not shown in FIGS. 18A-18D and 22) asdescribed above. While it is not shown in FIG. 22, it is envisioned thatadditional structures, such as a pusher 1130, shown in FIGS. 18A-18D and19A-19D may be used to deploy the device at the desired location. Thepusher will typically be formed from a rigid non-interactive material,such as Teflon™ or other polymer approved for surgical applications.

The guide element 220 can be fabricated from a variety of materials toachieve the desired mechanical properties and bio-compatibility. Theguide element 220 may be constructed from metal, e.g., wire, e.g.,stainless steel wire, or nickel alloy wire. The guide element may beconstructed from natural fibers, such as cotton or an animal product.The guide element may be constructed from polymers, such asbiodegradable polymers, such as polymers including repeating lacticacid, lactone, or glycolic acid units, such as polylactic acid (PLA).The guide element may also be constructed from high-tensile strengthpolymers, such as Tyvek™ (high-density polyethylene fibers) or Kevlar™(para-aramid fibers). In an embodiment, guide element 220 is constructedfrom biodegradable suture, such as VICRYL™ (polyglactin 910) sutureavailable from Ethicon Corp., Somerville, N.J.

The guide element 220 can be coupled to the self-closing or self-openingdevice with a number of different configurations and attachmentmechanisms. Additionally, the guide elements can be used in the sameconfigurations regardless of the magnetic polar configuration of thedevices. The guide element may be simply tied to the device, or theguide element 220 can be attached to the device with an adhesive, e.g.,acrylate glue, or with a fastener, such as a clip, screw, or rivet.

In other embodiments, such as shown in FIGS. 19A-19D and 23, the guideelement 220 may be attached to, or configured to interact with, morethan one part of the device. For example, FIGS. 19A-19D show aself-opening device, wherein a guide element 220 is coupled to thedistal-most segment of a self-opening device, and configured to interactwith radial members 510 that facilitate assembly and placement of thedevice. Alternatively, as shown in FIGS. 20A-20D, two guide elements 220may be coupled to the hinges to facilitate conversion from a deliveryconfiguration to a deployed configuration. It should be noted that theguide elements 220 shown in FIGS. 20A-20D would be on top of each otherand taught when pulled, but have been shown apart for ease of viewing.Additionally in FIGS. 20A-20D, the pusher 1130 can be used to manipulatethe device once it has achieved a deployed configuration. Also, as shownin FIG. 23, a guide element 220 may be coupled to the distal-mostsegment of a self-closing device, and configured to interact with radialmembers 510 that facilitate assembly and placement of the device.Furthermore, as shown in FIG. 23, proximal force on the guide element220 helps the device to close. As shown in FIGS. 19A-19D and 23, theradial members 510 also establish a center 530 of the device, which iscoupled to the guide element 220 when the device has achieved adeployment configuration and the guide element 220 is pulled taut. Thecenter 530 of the device can then be delivered to a desired location,e.g., opposite a mating device on the other side of a tissue.

FIGS. 21A-21D show a different delivery technique, in which a guidewire1250 is delivered to the area where an anastomosis is to be formed,after which a self-opening device can be delivered to the location usinga pusher 1130 (motion shown with hashed arrow) while a sheath 1220(motion shown with black arrow) is used to keep the self-opening devicein a delivery configuration. Once the device has been delivered to thearea, the sheath 1220 can be removed proximally, thereby allowing theself-opening device to transform to a deployment configuration. Once thesheath 1220 has been retracted suitably, the pusher 1130 can be used toplace the device or help it to mate with a joining device. The deliveryand deployment may be visualized, e.g., with fluoroscopy or ultrasound,and the device and the pusher 1130 may include markers, such asradiopaque markers, to facilitate visualization. Additionally, while notshown in FIGS. 21A-21D, the device may include one or more guideelements 220 to improve deployment or to facilitate placement.

Like the guide elements 220, the radial members 510 can be fabricatedfrom a variety of materials to achieve the desired mechanical propertiesand bio-compatibility. The radial members 510 may be constructed frommetal, e.g., wire, e.g., stainless steel wire, or nickel alloy wire. Theguide element may be constructed from natural fibers, such as cotton oran animal product. The guide element may be constructed from polymers,such as biodegradable polymers, such as polymers including repeatinglactic acid, lactone, or glycolic acid units, such as polylactic acid(PLA). The guide element may also be constructed from high-tensilestrength polymers, such as Tyvek™ (high-density polyethylene fibers) orKevlar™ (para-aramid fibers). In an embodiment, the radial members 510are constructed from biodegradable suture, such as VICRYL™ (polyglactin910) suture available from Ethicon Corp., Somerville, N.J. Additionally,the radial members 510 can be used in the same configurations regardlessof the magnetic polar configuration of the devices.

EXAMPLES Example 1: Calculation of Azimuthal Potentials

Azimuthal patterns were calculated for each of the self-openingconfigurations shown in FIGS. 24-29.

The calculations begin with the assumption of perfect repulsive symmetryacross the centerline of the self-opening rings, the line between thetwo internal hinges at either end of the delivery configuration and itstwo parallel rows of four magnet segments. With this assumed symmetry weneed only enumerate the possible combinations of N's and S's along oneof the four-segment ‘sides.’ There are only 16 such arrangements, 2⁴,which can be easily spelled out:

 1) NNNN  2) NNNS  3) NNSN  4) NSNN  5) SNNN  6) NNSS  7) NSSN  8) SSNN 9) SNNS 10) SNSN 11) NSNS 12) NSSS 13) SNSS 14) SSNS 15) SSSN 16) SSSSBecause of centerline mirror symmetry, it can't matter from which end westart with the calculation. A pattern left-to-right must be the sameentity as the same pattern from right-to-left, as well as being the sameas the ‘reverse pattern (N/S swap equivalent to a ring flip)’ in eitherdirection. So 1=16, 2=15=5=12, 3=14=4=13, 6=8, 7=9, 10=11 and there areonly 6 distinct patterns: 1,2,3,6,7,10

Configuration 1=16)=FIGS. 9A, 9B, and 24. Configuration2=5)=12)=15)=FIG. 25. Configuration 3=4)=13)=14)=FIG. 26. Configuration6=8)=FIGS. 9C and 27. Configuration 7=9)=FIGS. 9D and 28. Configuration10=11)=FIGS. 10A and 29.

The azimuthal properties of each pattern were calculated by drawing eachoctagonal magnet pattern onto duplicate mylar sheets. The potentialenergy of each segment's interaction with its mating neighbor is either−1, +1 or 0, attractive-repulsive-neutral. [As an approximation, each ofthe two inserted quadrupolar segments are deemed to have no interactionwith any dipole segment; however a full interaction when one quadrupolarsegment aligns with other quadrupole.] After the initial calculation,one of the mylar sheets is rotated 45 degrees and the new potentialenergy tabulated. Repeating this rotation and calculation step eighttimes results in a list of 8 numbers that describe the rings'interaction through one complete in-plane revolution relative to theother. Additional details of the calculations are presented below.

The numbers from the calculation are tabulated in an octagonal array(i.e., 12, 1:30, 3, 4:30, 6, 7:30, 9, 10:30 on a clockface) where anadjacent number represents the potential energy of the rings after 45degree rotation of one of the rings. The potential energy of thering-pair is actually a smooth curve connecting these most easilycalculated locations. Using this presentation, we can tabulate theazimuthal behavior of the six distinct patterns shown in FIGS. 24-29 (2Qversions thereof) as well as the potential energy of a closed ring (onthe right), the sum of the miter interactions (compared with −8 of theearlier, completely self-assembling rings).

 (1) −8 −8 −8 −8 −8 −8 −8 −8 8 repel (R) +8  (2) −8 −2 0 −2 0 −2 0 −2 4attract (A)/4 repel (R) 0  (3) −8 +2 0 −2 0 −2 0 +2 6A2R −4  (6) −8 0 00 +8 0 0 0 4A4R 0  (7) −8 0 +4 0 −8 0 +4 0 6A2R −4 (10) −8 +4 0 −4 +8 −40 +4 8R +8Upon making the calculations, the following trends are noted:Configuration 1 (FIG. 24) is unique in the absence of variation ofattractive force with rotation. While there is no azimuthal variation,the lack of rotational force could potentially lead to mismatcheddevices and deviation in size and shape of the anastomosis. However,with proper placement, it is unlikely that the lack of rotational wellswill be problematic. It is noteworthy that all of the mitered joints arerepulsive in Configuration 1 (or almost all, if quadrupole segments areused at the end). For this reason, it may be beneficial to deployself-opening devices of configuration 1 using guide elements, e.g., asdiscussed above.Configuration 2 (FIG. 25) Numerous attractive wells, only one fulldepth.Configuration 3 (FIG. 26) Numerous attractive wells, only one fulldepth, surrounded by 25% repulsive barriers.Configuration 6 (FIG. 27) Good potential. While Configuration 6 hasrotational potential wells, the wells are well-defined and aid alignmentof the devices. Additionally, the force at a distance is almost asstrong as Configuration 1. See, e.g., FIG. 7.Configuration 7 (FIG. 28) Good potential. Slightly less force at adistance, rotational wells facilitate alignment, but provide moremaneuverability because there are two equal wells with 180° of rotationof one device.Configuration 10 (FIG. 29) Numerous potential wells, only one fulldepth, flanked by 50% repulsive barriers; the multiple rotational wellsmay make alignment more difficult.

Calculation of the repulsive and attractive forces for each self-openingconfiguration, with and without quadrupole end segments, is calculatedas detailed, below. Each configuration, i.e., as shown in FIGS. 24-29,has multiple diagrams, noted i, ii, iii, . . . viii. (Cross-hatched isN, solid is S.) Diagrams i, ii, and iii depict the configuration withoutquadrupolar segments, i.e., “nonQ” versions, whereas iv, v, and viiirepresent the configuration with the addition of one quadrupolarmagnetic segment at each end, i.e., the “2Q” versions.

Because there is repulsion across each inner hinge, there is someadvantage of adding an additional reversal, a quadrupole segment, thatallows for attraction across what is otherwise repulsive miter. (Noshort range loss of force; some loss on long range interaction.) This 2Qversion, with one for each inner hinge, is depicted in diagrams iv, v,and viii. (There are actually two ways to introduce the Q's, mirrorimages across the centerline. They are non-superimposable mirror imageswith equivalent behavior.)

Separately, each configuration includes a diagram vi that is a depictionof the ring's rotational interaction (nonQ numbers outside, 2Q numbersinside). With both rings perfectly aligned there is a maximal 8 units ofattraction between all mated segments, depicted as −8 implying apotential energy well. As one magnet is held fixed and the other isrotated to one of the other 7 aligned positions the new potential energyof the ring couple is displayed there accordingly. +8 represents acondition of complete repulsion between all 8 pairs and 0 a balancebetween 4 attractive and 4 repulsive segment pairs. −2 slightattraction. +2 slight repulsion. The lower the number the greater therings' total attractive force in that orientation. Additionally, thereis an applied torque proportional to the change in energy as function ofazimuthal angle. Configuration 1, diagram vi shows that coupling ofthese ‘unipolar rings’ would not require rotation, nor could couplinginduce rotation. Configuration 2, diagram vi shows that the 2Q (inner)version would have distracting weak minima at 4:30 and 7:30 from thereal direction. Configuration 3, diagram vi shows strong ‘half-deep’wells in the nonQ configuration may make alignment tricky during aprocedure. Configuration 6, diagram vi suggests beneficial propertiesboth in terms of alignment and closing, and has favorable long-distanceproperties, as discussed above. Configuration 7, diagram vi suggeststhat configuration 7 doesn't have to rotate as far as configuration 6,but has slightly inferior long distance interactions. Configuration 10,diagram vi, suggests a variety of local minima, which may result indisfavored performance. Configuration 10 additionally experiences lessattractive force at a distance, which may make coupling more difficultthrough, e.g., thick tissues.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1-20. (canceled)
 21. A self-opening magnetic compression anastomosis device comprising: an assembly comprising: a first cluster comprising a plurality of magnetic segments coupled end-to-end, and a second cluster comprising a plurality magnetic segments coupled end-to-end, a first connection member connected to a magnetic segment of the first cluster and a magnetic segment of the second cluster; a second connection member connected to a magnetic segment of the first cluster and a magnetic segment of the second cluster; a first polygon-opening member coupled to at least two magnetic segments of the first cluster; and a second polygon-opening member coupled to at least two magnetic segments of the second cluster, wherein the assembly comprises: a delivery configuration wherein the magnetic segments of the first cluster form a first row and the magnetic segments of the second cluster form a second row and wherein each of the first connection member and the second connection member joins an end of the first row to an end of the second row, and a deployed configuration wherein the magnetic segments are coupled end-to-end to form a polygon comprising a plane and having an out-of-plane axis.
 22. The magnetic compression device of claim 21, wherein: the magnetic segments connected to the first connection member have north poles aligned relative to one another with respect to the out-of-plane axis when the assembly is in the deployed configuration, and the magnetic segments connected to the second connection member have north poles aligned relative to one another with respect to the out-of-plane axis when the assembly is in the deployed configuration.
 23. The magnetic compression device of claim 22, wherein the north poles of the magnetic segments connected to the first connection member are aligned with the north poles of the magnetic segments connected to the second connection member.
 24. The magnetic compression device of claim 22, wherein the north poles of the magnetic segments connected to the first connection member are anti-aligned with the north poles of the magnetic segments connected to the second connection member.
 25. The magnetic compression device of claim 21, wherein adjacent magnetic segments in the deployed configuration have north poles that alternate in orientation with respect to the top and bottom of the polygon.
 26. The magnetic compression device of claim 21, wherein, when the assembly is in the deployed configuration: the first polygon-opening member is coupled to an exterior surface of the at least two magnetic segments of the first cluster, and the second polygon-opening member is coupled to an exterior surface of the at least two magnetic segments of the second cluster.
 27. The magnetic compression device of claim 21, wherein: the first polygon-opening member is coupled to each magnetic segment of the first cluster, and the second polygon-opening member is coupled to each magnetic segment of the second cluster.
 28. The magnetic compression device of claim 27, wherein: the first polygon-opening member restricts movement of the magnetic segments of the first cluster relative to the plane of the polygon, and the second polygon-opening member restricts movement of the magnetic segments of the second cluster relative to the plane of the polygon.
 29. The magnetic compression device of claim 28, wherein: the first polygon-opening member prohibits movement of the magnetic segments of the first cluster out of the plane of the polygon, and the second polygon-opening member prohibits movement of the magnetic segments of the second cluster out of the plane of the polygon.
 30. The magnetic compression device of claim 21, wherein a force exerted by the first polygon-opening member on the at least two magnetic segments coupled to the first polygon-opening member and a force exerted by the second polygon-opening member on the at least two magnetic segments coupled to the second polygon-opening member promote transition of the assembly from the delivery configuration to the deployed configuration.
 31. The magnetic compression device of claim 21, wherein each of the first connection member and the second connection member comprises a hinge.
 32. The magnetic compression device of claim 21, wherein the polygon is selected from the group consisting of a square, a rectangle, a hexagon, and an octagon.
 33. A self-opening magnetic compression anastomosis device comprising: an assembly comprising: a first cluster comprising a plurality of magnetic segments coupled end-to-end, and a second cluster comprising a plurality magnetic segments coupled end-to-end, a first connection member connected to a magnetic segment of the first cluster and a magnetic segment of the second cluster; a second connection member connected to a magnetic segment of the first cluster and a magnetic segment of the second cluster; a first radial member having a proximal end and a distal end, the distal end being coupled to a magnetic element in the first cluster; a second radial member having a proximal end and a distal end, the distal end being coupled to a magnetic element in the second cluster; and a guide element having a proximal end and a distal end, the distal end being coupled to the proximal ends of the first radial member and the second radial member, wherein the assembly comprises: a delivery configuration wherein the magnetic segments of the first cluster form a first row and the magnetic segments of the second cluster form a second row and wherein each of the first connection member and the second connection member joins an end of the first row to an end of the second row, and a deployed configuration wherein the magnetic segments are coupled end-to-end to form a polygon comprising a plane and having an out-of-plane axis.
 34. The magnetic compression device of claim 33, wherein: the magnetic segments connected to the first connection member have north poles aligned relative to one another with respect to the out-of-plane axis when the assembly is in the deployed configuration, and the magnetic segments connected to the second connection member have north poles aligned relative to one another with respect to the out-of-plane axis when the assembly is in the deployed configuration.
 35. The magnetic compression device of claim 34, wherein the north poles of the magnetic segments connected to the first connection member are aligned with the north poles of the magnetic segments connected to the second connection member.
 36. The magnetic compression device of claim 34, wherein the north poles of the magnetic segments connected to the first connection member are anti-aligned with the north poles of the magnetic segments connected to the second connection member.
 37. The magnetic compression device of claim 33, wherein adjacent magnetic segments in the deployed configuration have north poles that alternate in orientation with respect to the top and bottom of the polygon.
 38. The magnetic compression device of claim 33, wherein a site of coupling of the distal end of the guide element to the proximal end of each of the radial members comprises an approximate center of the polygon when the assembly is in the deployed configuration.
 39. The magnetic compression device of claim 33, wherein the device comprises a plurality of first radial members and a plurality of second radial members.
 40. The magnetic compression device of claim 33, wherein each of the first connection member and the second connection member comprises a hinge. 